Needle monitoring device for circular knitting machines

ABSTRACT

A needle monitoring device for circular knitting machines comprises a sensing device for detecting the needles moving past said sensing device and for generating an impulse for each detected needle, a preselection counter pre-set to the correct number of the needles, and a feeler detecting start and end of each machine revolution. A logic circuit receives signals from said preselection counter and said feeler and delivers a warning signal when the pre-set number has not been reached after one revolution of the machine.

United States Patent [1 1 Brose Jan. 29, 1974 [75] Inventor: PeterBrose, Wolfratshausen,

Germany [73] Assignee: Firma Erwin Sick, An der Allee,

Germany [22] Filed: Mar. 8, 1972 [21] Appl. No.: 232,712

Lawson et a1 66/ 157 2,760,363 8/1956 Van Alen et a1. 66/157 3,324,6856/1967 Schmidt et al...... 66/154 A 3,496,739 2/1970 Motin et al. 66/163Primary Examiner.lames Kee Chi Attorney, Agent, or Firm-Darbo, Robertson&

Vandenburgh [5 7] ABSTRACT 2 Claims, 3 Drawing Figures b NUMBER [52][1.8. CI. 66/157, 66/163 [51] Int. Cl D04b 35/10 [58] Field of Search66/157, 163, 166, 165

[ 56] References Cited UNITED STATES PATENTS 3,646,542 2/1972 Anthony66/157 X 3,529,445 /1970 Brose 66/157 3,577,750 5/1971 Venczez 66/1573,659,437 5/1972 McArthur et a1.. 66/157 3,509,739 5/1970 Gottschall66/157 (REVOLUTION DETECTOR KNITTING RIB CYLINDER I NEEDLE I ozrscronMACHINE OPERATION CONTROL FIXED COUNTER I I l 1 Y 1 I I 1 BACKGROUND ANDSUMMARY OF THE INVENTION This invention relates to a needle monitoringdevice for circular knitting machines comprising a sensing device fordetecting the needles moving past said sensing device and for generatingan impulse for each detected needle.

In a prior art needle monitoring device of this type (my U.S. Pat. No.3,529,445) there is a sensing device producing an impulse for eachdetected needle and thus a composite a.c. output signal. An evaluatingcircuit is connected to the sensing device, said evaluating circuitresponding to irregularities of the a.c. signal, namely to the timeinterval between consecutive impulses delivered by the sensing device onthe basis solely of reflections from the needle. The prior art devicemakes use of the fact that both a broken and a bent needle results in achange of the time interval between consecutive needle impulses. If aneedle is broken, the time interval from the previous needle impulse tothe next needle impulse is twice the normal value. A bent needle resultsin a shorter time interval between a first pair of needle impulses and alonger time interval to the next following needle impulse or vice versa.In the prior art device, the evaluating circuit comprises an integratingnetwork to which a constant input signal is applied, said integratingnetwork being connected to be reset by the impulses delivered by thesensing device A tripper device is provided which responds as soon asthe output of the integrating network exceeds a desired threshold.

Knitting machines can have variations in the time interval betweenconsecutive needle impulses during a machine revolution due to needlevibrations without any needle being broken or deformed. While these donot affect the operation of the knitting machine, they can improperly beinterpreted by the aforesaid prior art devices as indicating a broken orbent needle.

It is' an object of the invention to provide a needle monitoring devicefor circular knitting machines, in which only needle impulses areprocessed and which operates in a purely digital manner.

- The. needle monitoring device of the invention is characterized by a.a preselection counter pre-set to the correct number of the needlesandconnected to count the needle impulses, said preselection counterproducing different output signals depending on whether the pre-setnumber has been reached or not,

b. a feeler for detecting start and end of a machine revolution and c. alogic circuit providing a logic configuration of the signals from saidpreselection counter and said feeler to produce a warning signal, whenthe preset number has not been reached after one revolution of themachine.

Preferably in embodiment of the invention the output signal of saidpreselection counter is changed from L to 0 upon reaching said pre-setnumber; the preselection counteris reset to zero at the beginning of thenext revolution of the machine; and the feeler produces a signal 0during each revolution of the machine and a signal L upon completion ofeach revolution; and the two signals from the preselection counter andfrom the feeler are logically combined by an AND-gate.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow diagram" of a device of theinvention;

FIG. 2 shows the associated pulse time diagram; and

FIG. 3 is a perspective and diagrammatic view of part of a conventionalknitting machine having photoelectric detectors according to theinvention.

DESCRIPTION OF SPECIFIC EMBODIMENT The drawings illustrate a circularknitting machine I the revolutions of which are detected by a feeler 2which may take the form of a photoelectric detector looking at a stripe10 on the cylinder of the knitting machine. Feeler 2 delivers an outputsignal 0,." duringeach revolution and an output signal L, between thethe revolutions. That is, when the photoelectric detector 2 is lookingat the stripe 10 the 0, signal results, while when it is looking at thegap 11 between the ends of the stripe the L, signal results. This hasbeen shown in the first line of FIG. 2. Two photoelectric detectors 3and 4 detect the rib needles l2 and the cylinder needles 13 respectivelywhen these needles are moved past said sensing heads. The impulsesreceived from the sensing heads 3 and 4 are counted by a counter 5 whichhas been preset to count only to a given number. When the machine has ncylinder needles and n rib needles, the sum of all needles provided onthe machine is n n n ..The counter is pre-set to this number. Thecounter delivers an output signal L as long as the pre-set number hasnot yet been reached. Upon reaching the pre-set number, the outputsignal of the preselection counter 5 is changed to 0 The output signalsof feeler 2 and counter 5 are applied to the two input terminals of anAND-gate 6. The output of the AND-gate 6 controls the operation of themachine, as indicated at 7.

During the first revolution (the left side of FIG. 2), all needleimpulses are present. It will be noted that during the first revolutionand during the interval between it and the second revolution either thesignal from feeler 2 or the signal from counter S is O, at the inputterminals of AND-gate 6. Thus nothing passes through the AND-gate 6. Atthe beginning of the second revolution, the counter has already beenreset to zero because it had counted out (up to the preset number) bythe end of the preceding revolution. In FIG. 2 it is assumed that a ribneedle is missing at 8 during the second revolution, so that one impulseis missing accordingly. Thus the counter does not reach the presetnumber during this revolution and the output of the counter does notreturn to 0 The signal L then continues beyond the termination of thesecond revolution. Thus, when the output of feeler 2 becomes also (L,)at the end of the second revolution, the AND-gate delivers acorresponding signal (L,,) which (see last line of FIG. 2) causes themachine to be switched-off immediately following the end of the secondrevolution.

The device described can be used in addition to a monitoring devicedescribed in US. Pat. No. 3,529,445, in order to provide an additionalcheck and to eliminate mistaken operations which could occur in a deviceof this patent due to needle vibrations. Of

course, only one pair of photoelectric sensing heads need be provided,the impulses of which are, on one hand, counted. and, on the other hand,checked for their time intervals.

As will be apparent to anybody skilled in the art, L and O are twobinary states. For example, L may mean voltage" and may mean no voltage"or vice versa.

The revolution feeler may be of any conventional type and may, forexample, comprise a slip ring or, alternatively, photoelectric means.

I claim:

1. In a needle monitoring device for use with a circular knittingmachine operating in revolutions with intervals between revolutions andhaving a given number of needles, said device having needle detectormeans producing an impulse each time a needle passes said means, saiddevice comprising:

revolution detector means for detecting the start and end of a machinerevolution and for indicating whether the machine is performing arevolution or in the interval between revolutions;

counter means connected to said needle detector means to count saidimpulses to said number repeatedly and to indicate whether it is in theprocess of counting to said number or is awaiting an impulse to commencesaid count; and

circuit means connected to said revolution detector means and to saidcounter means to produce an error signal when the count in the countermeans has not reached said number by the end of a revolution. 2. In aneedle monitoring device for use with a circular knitting machineoperating in revolutions with intervals between revolutions and having agiven number of needles, said device having needle detector meansproducing an impulse each time a needle passes said means, said devicecomprising:

revolution detector means for detecting the start and end of eachrevolution of said machine and producing output signals of one typeduring the revolutions and producing output signals of a second type inthe interval between revolutions; counter means connected to said needledetector means to count said impulses to said number repeatedly andproducing output signals of said one type while it is in the process ofcounting up to said number and of said second type after the countreaches said number and before the count recommences; and V circuitmeans connected to the revolution detector means and to the countermeans to produce an error signal when said signals of said one typeoccur simultaneously.

:.-UNITED STATES PATEN OFFICE CER'TIFICATE OF CORRECTION Patent No.3,788,'l05 Dated January 29, 1974 Inventor(s) Peter Brose dIt iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected 'as shown below:

In the address of the Assignee, delete. "An der Allee. and insert-Waldkirch-.

Signed and. sealed this 11th dayof June. 197k;

(SEAL) I v Attest: V I

EDWARD H.FLETC-HER,JR. c. MARSHALL 1mm Attesting Officer Commissioner ofPatent;

-'ORM PO-1050 (10 69) USCOMM-DC 60375.]:59

' us, GOVERNMENT manna omc: inn o-ua-au.

1. In a needle monitoring device for use with a circular knittingmachine operating in revolutions with intervals between revolutions andhaving a given number of needles, said device having needle detectormeans producing an impulse each time a needle passes said means, saiddevice comprising: revolution detector means for detecting the start andend of a machine revolution and for indicating whether the machine isperforming a revolution or in the interval between revolutions; countermeans connected to said needle detector means to count said impulses tosaid number repeatedly and to indicate whether it is in the process ofcounting to said number or is awaiting an impulse to commence saidcount; and circuit means connected to said revolution detector means andto said counter means to produce an error signal when the count in thecounter means has not reached said number by the end of a revolution. 2.In a needle monitoring device for use with a circular knitting machineoperating in revolutions with intervals between revolutions and having agiven number of needles, said device having needle detector meansproducing an impulse each time a needle passes said means, said devicecomprising: revolution detector means for detecting the start and end ofeach revolution of said machine and producing output signals of one typeduring the revolutions and producing output signals of a second type inthe interval between revolutions; counter means connected to said needledetector means to count said impulses to said number repeatedly andproducing output signals of said one type while it is in the process ofcounting up to said number and of said second type after the countreaches said number and before the count recommences; and circuit meansconnected to the revolution detector means and to the counter means toproduce an error signal when said signals of said one type occursimultaneously.